In a semiconductor device manufacturing process, there has been known a process of forming a hole or a trench in a multilayer film formed on a semiconductor wafer (hereinafter, referred to as “wafer”) through a resist mask formed on the multilayer film by an etching gas suitable for each film by using a single etching apparatus. However, a deposit may be deposited to a peripheral portion or a backside of the wafer during the above process. This is because an etching residue is adhered to the wafer in a dry etching process and a film forming gas flows toward the backside of the wafer in a film forming process. The deposit may cause particles when the wafer is transferred or processed in a next process. Therefore, the deposit needs to be removed. As for a method for cleaning a deposit firmly adhered to the peripheral portion of the wafer, brush cleaning using a resin material, CMP (Chemical Mechanical Polishing) or the like has been conventionally used. However, such a method is mechanical and may cause secondary contamination from the cleaning members. Further, water is used for the cleaning, so that an adverse effect from water may be caused. In other words, if a thin film on the wafer is made of a soluble material, elution may occur or a low dielectric film such as SiCOH or the like may be damaged.
International Publication No. 2010/021265 discloses a technique for etching or planarizing a semiconductor substrate or a thin film layer on a surface of the semiconductor substrate by ejecting a gas cluster to the semiconductor substrate without ionizing the gas cluster. However, a technique for cleaning a peripheral portion of a wafer is not disclosed therein.
Further, Japanese Patent Application Publication No. 2007-232901 discloses a technique for removing a photoresist film by ejecting particles of dry ice toward a wafer. However, when the particles of the dry ice are ejected to the wafer to remove a polymer adhered to the wafer W, the wafer may be broken or secondary contamination from the dry ice may occur.